Inner tube



J. w. wABER `lune 6,. 1939.

INNER TUBE Filedy Nov. l, 1957 VPatent-ed June 6,1939

UNITED. STATES'.

PATENT OFF-ICB??,'

This invention relates'to improvements in inner tubes and the process of making vand particularly to a' tube such as is commonly referred to as a l puncture-proof tube, or more; accurately as a l self-sealing tube.

Ihe present invention is a moditlcationbf the tubes disclosed in applicants. Patents 1,808,091 and 2,033,962 and may be made by the methods described in said patents, although its manufac# 1o -ture is not limited to the use of the previously de-` scribed methods.

The tubeherein disclosed diiers from the tube of the above noted patents in that the mastic, or unvulcanizable plastic material, is divided longitudipauy into a plurality of strips by intervening partitions of vulcanizable material.

When selfsealing tubes 'havingplastic type rubber compounds in the tread portion thereof are used .in tires on vehicles that are driven at exceedingly high speeds for long periods of time, without occasionally dropping toy aver e or low speed, as for instance in racing cars, there is a tendency-for the centrifugal force tothrow the plastic-material toward the center-line of the tube and away from the portion of .the tube usually termed the shoulder, causing the plastic,

Amaterial to become of increased ckne'ss at the ter of .the tread portion and of less thickness *a "the sides of the tread portion. .This diminishes theamountof puncture protection at the shoulders of the tire, i. e., at the areas in yrhich the Irma-y be nere noted that, dueto the nature of f the plastic material, displacement thereof does 40 not 'occur to any distinguishable degree unrd-er ordinary use, even 'athigh speeds, when the periods of high speed are interspersed with a' fair percentage of periods of avrage'driving speed.

' However, there are occasions when it is desirable to have an eilicient self-'sealing tube of the y plastic sealing type that can be successfully used at sustained high speeds for` long periods andthe present tube fulfils this requirement.

' -It is believed 'the' further disclosure 10i" the"l inventlon will 'be'readlly understood .from a de-V tailed description thereof takenin connection'- withA the accompanying drawing 'in which Fig.-1shows a cross'section of the basictube. 55" element' winch vmaybe of substantially'the same character as non-self-'sealing tubes now -on the market; and 1 Fig. 2 is a cross section through the completed tube, showing the partitionsor 'bailles .of vulcanirable material which separates' the plastic sealing compound into longitudinal strips, i 5

Referring now to the drawingin which like reference characters indicate the same parts in bothviews y The basic tube. I0, of vulcanizable material, has

- applied to the tread.portion thereof acrescent- 10 shaped layer^ of plastic material comprising the central strip 'I2 and the side strips Il. .Extending longitudinally of the plastic material and providing'partitions or baiiles between the central plastic section I2` and the side sections Ilare 1? 'the strips Il of vulcanizable material, the inner edges of strips I4 being joined to the basic tube I0, as by vulcanization thereto and the outer edges being rmly secured tothe cover layer I5 of vulcanizable material. 20 The preferred method of making the tube .of the present invention will now'be described. The basic tube I0 isrst formed as an annular, endless tube 'of -a size slightly smaller than the cavity withinthe casing with which itis to be 25 used. A valve stem (not shown), is nmext' inserted in tube I0 and it is inilated to a point where it is fully expanded but under. little if any, tenson,i. e., to about the 'size it'will have when the tube ls completed. 'Ihe expanded tube I0 is now 30 mounted on a revolving building drum', preparatory to placing the mastic material and cover strip thereon. The process so far is the same as described in the above-mentioned patents.

The'following steps in the present process 35 diiler from previous disclosures. Along the center A'theii'inner-encls are arranged to engage the tube I0 as indicated at Ila. The strips I3 of plasticv material are then/placed on the tread portion of tube I0,one on each side of the centralstrip I2 and in engagement with-.the bailles Il, respec- 45 tively.A A cover strip I5 of vulcanizable material is then placed over the mastic strips with its yopposite edges in engagement with the tube III.

'Ihe outer edges` oil the bailies "il are arranged to be engaged by the cover strip I5 as. indicated 50 at Mb. l

From this point the process may be such as deamould of the correct size land shape and heat applied, the internal pressure of the tube being smooth and inishedv exterior. When the proper time has elapsed, the heat is withdrawn'and the finished tube removedfrom the mould, which completes theA process. The inner edges of the partitions Il are now firmly vulcanized to the basic tube I0 and the outer edges of the partitions will be vulcanized to the cover strip I5.

Patent 2,033,962. disclosesY the expedient of treating the tread portion of the basic tube III, which underlies the cover layer, prior to vulcanization, with a vulcanization accelerator to `increased to amamount sufllcient to insure aA insure a ltight cure of this portion of the basic tube. 'I'he partitions, or bailies, I4 may be similarly treated.

In the interest of clearness and ease of dis' closure, but two bailles, or partitions, are shown on the drawing and described. Two bailles are usually suflicient, although it is obvious that as many baiiles may be provided as are desired or found necessary. The number of bailles required maybe influenced to a certain extent by the consistency of the plastic material I3. Y.

While above, the tube has been described as preferably made on an air mandrel, it is believed that its manufacture is not limited to this expedient.

Having thus describedv my. inventibn, what `Iy claim as new and desire to secure by Letters Patent of the United States is:

1. The method of constructing an inner tube for pneumatic tires, which consists infexpanding abasic ,endless tube of 'vulcanizabletmaterial byA internal pressure, superimposing upon the tread portion of said tube while so expanded alternate strips of unvulcanizable sealing compound and separator strips of vulcanizable material, the

inner edges of said separator strips engaging said endless tube andl the outer edgesrof said separator strips extending to the `outer surface of said strips of sealing compound, said strips of@ sealing compound and said separator strips being arranged longitudinally of said endless tube and in contact with each other, placing a cover sheet of vulcanizablematerial over said sealing compound and said 'separatorstripa and curing the whole tubestructure while expanded in a mold to cause the vulcanizable cover sheet to become vulcanized to the basic 'tube at its edges and causing the separator ,strips tobecome vulcanized tol `said endless tube at their inner edges and to V the cover sheet at their outer edges.

2. Themethod of constructing aninner tube for pneumatic tires, which consists in expanding internal pressure, superimposing upon the tread portion of said tubewhilebsoexpanded alternate strips of unvulcanizable sealing compound and separator strips of vulcanizable material, the two opposite outermost strips being of unvulcanizable. material, the inner edges of said separator strips engaging said endless tube and the outer edges' of said separator strips extending to the outer surface of said strips of sealing compound, said strips of sealing compound and said separator strips being arranged longitudinally of said edless tube and in contact with each other, coveringL the sealing compound and separator strips with a sheet of vulcanizable material which ex-=` tends beyond the edges of the sealing compound and contacts with the basic; tube for adhesion thereto, and curing the whole tube structure.. while expanded, in a mold to causetheyulcaniz- 'an endless basic tube of vulcanizable material by edges of said sealing compound, respectively, the

inner edge of each of said separator strips being vin engagement with the basic tube, placing other strips of sealing compound on the tread portion of said basic tube, on the remote sides of said separator strips, respectively, covering the scaling compound and separator strips with a cover layer of vulcanizable material which extends` beyond .the .edges of the sealing compound and contacts with the endless tube for adhesion thereto and curing the entire tube structure, while expanded,

to cause the cover layer, the separator strips and the endlesstube to become firmly vulcanized together at their. contacting areas.

\ 4. The method of constructing an inner tube for pneumatic tires which consists in forming an endless basic tube of vulcanizable material, expanding said tube by internal pressure, placing on the outer circumference of said endless tube while inflated a longitudinallf extending strip of sealing compound, placing separator strips of vulcanizable material on the opposite lateral edges of said sealing compound, respectively, the inner edge of each of said separator strips being in engagement with the basic tube and the outer edge extending to the outer' surface oi said sealing compound, placing other strips of sealing compound on the tread rtion of said basic tube, on the remote sides of said separator strips, respectively, covering the sealing compound and separator strips with a cover layer of vulcanizable material `which extends beyond the edges of the sealing compound and contacts with the eiidless tube for adhesion-thereto and curing the entire tube structure, while expanded, to cause the cover layer, the separator strips and the endless tube to become rmly vulcanized together at their contacting areas.

-5. 'I'he method of constructing an inner tube for pneumatic tires which consists in forming anV endless basictube of vulcanizable material, expanding said tube by internal pressure, placing on the outer circumference of said tube, while inflated, a strip of sealing compound, placing separator strips` of vulcanizable material on the opposite lateral edges of said sealing compound, respectively, the inner edges of each of said separator'strips being in engagement with the basic tube, placing other strips of sealing compoundv on the tread portion of said basic tube,`on the remote sides of said separator strips, respectively, covering the sealing compound and separator strips with -a cover sheet of vulcanizable material which extends yond theedges of the sealing compound and contacts withA the endless tube for adhesion thereto and curing the entire tube structure, while expanded, causing the'cover sheet to become vulcanized .to the basic tubeat its edges and causing the' separator strips to become iirmly vulcanized to said endless tube at 

